The present invention generally relates to the sampling of fluid for testing and, more particularly, to an apparatus and methods for periodically sampling fluids from reactor vessels while reactions are in progress.
A variety of systems for sampling fluids from reactors and tanks are known. However, numerous disadvantages and shortcomings exist with prior systems, and there is a need for improvement to overcome such disadvantages and shortcomings.
Some examples of commercially-available prior fluid-sampling devices are the xe2x80x9cSafesamp Reactor Sampling Systemsxe2x80x9d sold by Technova AG, of Sweden, and the xe2x80x9cNeotecha Sampling Systemsxe2x80x9d sold by Grinnell Corporation, of Exeter, N.H.
The Safesamp system""s basic arrangement includes a flanged dip pipe for connection to the tank with the dip pipe extending downwardly into the fluid in the tank, a bottom flange with a suction hose mounted at the top and extending downward through the dip pipe and into the tank fluid and a perpendicular connection port in communication with the dip pipe to pressurize the tank. The bottom flange is connected to a flanged xe2x80x9cchargingxe2x80x9d ball valve. A middle flange is connected to the charging valve and has a sightglass with a ball float mounted on top and a perpendicular port located below the sightglass to direct flow for sampling. An upper flange is mounted on top of the sightglass and includes the sightglass ball seat, perpendicular connections for auxiliaries and a perpendicular port for a vent return. The perpendicular sampling port located in the middle flange is connected to a flanged isolation ball valve which is connected to the sampling assembly. The sampling assembly includes a sample bottle which is vented through another isolation ball valve which is connected to the vent return port in the upper flange.
To obtain a sample, the xe2x80x9cchargingxe2x80x9d ball valve is opened (the sampling isolation valve is closed) and the fluid is drawn up through the suction tube (by supplying, if needed, a vacuum via the upper flange connection or pressurizing the tank via the lower flange connection). The fluid flows upwardly, fills the perpendicular sampling port in the middle flange (to the isolation ball valve) and continues filling the sightglass. As fluid fills the sightglass, the ball float rises with the level until it reaches the top of the sightglass where the ball then seats against the ball seat located in the upper flange and flow stops. The operator closes the xe2x80x9cchargingxe2x80x9d ball valve and opens the sampling isolation valve and the vent valve. The fluid flows by gravity from the sightglass through the perpendicular sampling port in the middle flange, through the sampling isolation valve and into the sample bottle. Any entrapped gases are vented through the vent connection located between the sampling bottle and the vent return line.
The above-described sampling system has drawbacks in that the sample fluid volume would consist of partial previous sampling fluid if the system is not purged after each sampling, or would nonetheless consist of the first volume of fluid that is drawn from the top of the tank without any system fluid flushing first. It would be preferable to drain off the first and perhaps subsequent volumes of fluid so that the fluid sent to the sampling bottle is a sample that has not been mixed with previous samples or other contaminants. Such sampling system can only get an unmixed sample within the sampling bottle by drawing numerous cycles of fluid through the system. This is a time-consuming and inconvenient process, and is wasteful of the often expensive chemicals being mixed in the reactor vessel.
The aforementioned Neotecha systems, sold by Grinnell Corporation, are generally similar to the above-described Safesamp Samplers. The Neotecha system samples fluid from reactors for continuous media circulation and pH monitoring. The Neotecha samplers utilize double-diaphragm pumps and are relatively compact in design. The Neotecha samplers also use lined stainless steel braided hoses and connections to facilitate quick start-ups and convenient changes. They have a pH probe connection device which allows adaptation to most commercially-available pH probes, and various auxiliary ports to facilitate cleaning of wetted surfaces and additional vessel access.
However, the Neotecha systems have the problem that, when chemical compositions in the reactor vessel have particulates or become viscous to some extent, the compositions can tend to clog or damage the pump. This leads to costly down time for cleaning and repair.
These and other existing devices for sampling fluids from reactor vessels have significant problems. This invention addresses and overcomes such problems.
An object of the present invention is to provide an improved fluid-sampling apparatus which easily and reliably gives properly-representative samples from a reactor vessel.
Another object of this invention is to provide an improved in-process fluid-sampling apparatus which is reliably useful for a wide variety of reaction fluids, including mixtures with significant particulates and/or raised viscosities.
Yet another object of this invention is to provide an improved fluid-sampling apparatus which gives reliably-representative samples quickly, without any need for repeated withdrawal of fluids from the reactor vessel.
Another object of the invention is to provide an improved fluid-sampling apparatus which avoids waste of valuable reaction fluids.
Another object of the invention is to provide an improved fluid-sampling apparatus which avoids or minimizes significant downtime for cleaning and repair and which is easy to flush for cleaning and easy to disassemble for repair.
Still another object of the invention is to provide an apparatus for sampling fluid from a reactor vessel without contaminating the vacuum source used to draw the sample, while at the same time not requiring flushing of the sample or multiple cycling of the sample through a sight glass.
Another object of the invention is to provide improved fluid-sampling methods which overcome certain problems of existing methods and apparatus.
In accordance with the present invention, a vacuum assembly is provided for drawing fluid into an interior of an overflow tank from a fluid source. The vacuum assembly includes a vacuum source and a tubular conduit having a first end operatively connected to the vacuum source and a second end disposed within the overflow tank. An overflow element is provided for preventing the flow of fluid into the conduit in response to the fluid in the overflow tank reaching a predetermined level.
The conduit may include a vacuum port spaced from the second end of the conduit and a fill port disposed at the second end of the conduit. The overflow element is positioned within the conduit and is movable between a fill position wherein the vacuum source communicates with the interior of the overflow tank and a shut-off position wherein the interior of the overflow tank is isolated from the vacuum source. The overflow element is urged from the fill position and the shut-off position by fluid in the interior of the overflow tank. It is contemplated that the overflow element include a float ball.
In accordance with a still further aspect of the present invention, a fluid-sampling apparatus is provided for sampling fluid from a fluid source. The fluid-sampling apparatus includes an overflow chamber assembly defining an overflow chamber therein. A valve assembly interconnects the overflow chamber assembly and the fluid source. The valve assembly includes a valve movable between a first position and wherein overflow chamber communicates with the fluid source and a second position. A vacuum assembly is interconnected to the overflow chamber assembly for drawing fluid from the fluid source into the overflow chamber of the valve. The vacuum assembly includes a float valve cage disposed within the overflow chamber for limiting the fluid drawn into the overflow chamber to a predetermined level.
The vacuum assembly may include a tubular conduit having a first end operatively connected to a vacuum source and a second end operatively connected to the float valve cage. A seal having a central aperture is also provided. The central aperture of the seal allows the tubular conduit to pass therethrough. The seal has a sealing flange projecting radially from the central aperture which is captured between the vacuum assembly and the overflow chamber assembly. The sealing flange includes a recess therein which extends about the central aperture in the seal.
It is contemplated that the float valve cage include a vacuum port. An overflow element is disposed within the float valve cage. The overflow element is movable between a fill position wherein a vacuum source communicates with the interior of the overflow chamber through the vacuum port and a shut-off position wherein the interior of the overflow chamber is isolated from the vacuum source. The overflow element is urged from the fill position to the shut-off position by fluid in the overflow chamber. The overflow element includes a float ball.
In accordance with a still further aspect of the present invention, a fluid-sampling apparatus is provided for sampling fluid from a fluid source. The fluid-sampling apparatus includes an overflow chamber assembly defining an overflow chamber therein. A valve assembly interconnects the overflow chamber and the fluid source. The valve assembly includes a valve movable between a first position wherein the overflow chamber communicates with the fluid source and a second position. A vacuum assembly is interconnected to the overflow chamber assembly for drawing fluid from a fluid source into the overflow chamber through the valve. The vacuum assembly includes a float valve caged disposed within the overflow chamber for limiting the fluid drawn into the overflow chamber to a predetermined level. A sample bottle having an interior is operatively connected to the valve assembly. The interior of the sample bottle communicates with the overflow chamber with the valve in the second position.
An overflow element is disposed in the float valve cage. The overflow element is movable between a fill position wherein a vacuum source communicates within the interior of the overflow chamber through the vacuum port and a shut-off position wherein the interior of the overflow chamber is isolated from the vacuum source. The overflow element is urged from the float position to the shut-off position by fluid in the overflow chamber. The overflow element includes first and second float balls.